Modern electronic devices often require power conversion. For example, battery operated devices such as notebook computers and mobile phones often include microprocessors that require the batteries to supply low voltages and high currents. BUCK converter is a type of step-down converter often used in DC-DC power conversion applications. FIG. 1 is a schematic diagram illustrating a conventional BUCK converter. BUCK converter 100 is sometimes referred to as a synchronized BUCK converter because switches S1B and S2B are synchronized to alternately turn on or off.
Conversion efficiency and transient response are important parameters of step-down converters. Conversion efficiency determines how much power is lost during power conversion; transient response determines how quickly the converter can respond to load current or source voltage changes. In the conventional topology shown in FIG. 1, it is often difficult to both increase conversion efficiency and improve transient response since switch and parasitic losses are directly proportional to the switch mode frequency, while the value of the integrating inductor LBUCK determines the first order transient response and is inversely proportional.